Proppant dispensing system with knife-edge gate

ABSTRACT

A proppant container facilitates the transportation of wet sand for use in a hydraulic fracturing operation. A metering conveyor is positioned between a blender tub and a proppant motive mechanism, such as a conveyor or wash system that receives discharge direct from proppant containers of the type normally used to transport sand in support of a hydraulic fracturing operation. The metering conveyor is fitted with equipment including a knife-edge gate that may be used to facilitate flow control operations.

RELATED APPLICATIONS

This application is a divisional with respect to U.S. application Ser.No. 16/536,871 filed Aug. 9, 2019 and International ApplicationPCT/US2019/045952 also filed on Aug. 9, 2019, both of which applicationsclaims benefit of priority to U.S. provisional patent applications62/717,507 filed Aug. 10, 2018, 62/720,430 filed on Aug. 21, 2018, and62/876,973 filed Jul. 22, 2019, all of which are incorporated byreference to the same extent as though fully replicated herein.

BACKGROUND Field of the Invention

The presently disclosed instrumentalities pertain to the field ofcontainerized equipment for the transport of sand and, particularly, forthe delivery of sand or other proppant for use in hydraulic fracturingoperations.

Description of the Related Art

Hydraulic fracturing is a well-known well stimulation technique in whichpressurized liquid is utilized to fracture rock. In the usual case, thisliquid is primarily water that contains sand or other proppants thathold open fractures which form during this process. The resulting “fracfluid” may sometimes benefit from the use of thickening agents, butthese fluids are increasingly water-based. Originating in the year 1947,the use of fracturing technology has grown such that approximately 2.5million hydraulic fracturing operations have been performed worldwide by2012. The use of hydraulic fracturing is increasing. Massive hydraulicfracturing operations on shales now routinely consume more than amillion pounds of sand. Hydraulic fracturing makes it possible to drillcommercially viable oil and gas wells in formations that were previouslyunderstood to be commercially unviable. Other applications for hydraulicfracturing include injection wells, geothermal wells, and water wells.

The widespread use of hydraulic fracturing creates significant demandfor sand and other proppants. Considering the Permian Basin alone,demand has recently increased by almost 70% year over year. The Permianis thought to have consumed approximately 10.8 billion pounds ofproppant in 2017. The most common proppant in use is sand. Sandsuppliers typically mine or quarry the sand, sort it by size and dry thesand. The sand is then placed into containers and loaded onto trucks orrail cars for transport to a well site where there is a need for thesand. By way of example, U.S. Pat. No. 9,758,082 to Eiden III et al.,which is hereby incorporated by reference to the same extent as thoughfully replicated herein, shows one system for containerizing the sandfor use at a wellsite, as well as a conveyor sled for transporting thesand from the containers to a blending unit where frac fluid is mixed.

The cost of capital equipment for drying the sand is a limiting factorwhen developing new sand mining facilities. The price of sand reflectsthe cost of recouping this capital investment, together withtransportation charges from mines that are increasingly remote fromwhere the sand is used.

Frac sand is primarily silicon dioxide in an unconsolidated form and isfrequently mined when wet. The sand has a porosity that typicallyexceeds about 30% where all or part of this volume may be filled withwater. FIG. 1 is a midsectional view of a proppant container or pod 100like that described in Eiden III and illustrates a problem that happensif these prior art containers are filled with wet sand 102. The wet sandagglomerates into a mass that will not discharge properly from thecontainer 100. Either there is no discharge at all, or else sometimes ahole 104 may open down through the sand 102 above the discharge gate106. Water in the sand makes it difficult or impossible to unload thecontainer. For these reasons, conventional wisdom holds that the sandused as proppant in hydraulic fracturing operations needs to be dry.Accordingly, the sand is sieved and dried before it is mixed with fluidsin a blender tub. This may constitute a considerable expense wherehydraulic fracturing jobs may use several million pounds of sand.

In other challenges, changing governmental regulations and basicconcerns over worker safety present additional concerns for theindustry. New regulations are scheduled to become effective whichseverely restrict the exposure workers may receive of dust, especiallysilica dust from sand. In the United States, for example, theOccupational Safety and Health Administration is requiring employers tolimit exposure to respirable crystalline silica to 50 μg/m³ as aneight-hour time-weighted average. Employers in the hydraulic fracturingindustry must comply with these regulations by Jun. 23, 2021.

SUMMARY

The instrumentalities disclosed herein overcome the problems outlinedabove and advance the art by improving systems for transporting anddispensing sand during the performance of a hydraulic fracturingoperation. The system may advantageously utilize sand in wet or dry formwhere the sand is unprocessed in the sense that the sand has not beensieved to final grade and dried. As used herein, however, the term‘unprocessed sand” may include sand that has been screened through amesh having large openings such as ¼ inch, ½ inch, 1 inch, 1½ inch, or2-inch openings to remove debris such as roots, twigs, and larger rocks.Where the unprocessed sand may be dry sand, additional measures may beutilized for the control of dust. These advances are also beneficialwhen using processed sand.

In one aspect, where from 4% to 17% of the sand pore volume can retainwater when sand is wet, the inclusion of water in non-dried sandincreases the shipping cost by a negligible amount. Thus, there is noneed to dry the sand to save weight and corresponding transportationcharges. Past practices have, however, found it necessary to dry thesand for use in hydraulic fracturing due to the cohesiveness of wet sandcontributing to problems like that shown in FIG. 1. As used herein, “wetsand” means sand having at least 1% by weight of water, and may includesand having at least 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16% or more byweight of water. Slurried systems having more than about 10% or 20%water by weight may facilitate the flow of sand.

It has been discovered that a vibrator assembly may be used on thesecontainers in a manner that permits utilization of wet sand. Thisadvantageously permits regional sand quarries to mitigate the need forexpensive sand drying equipment and sand drying operations. The vibratorassembly disrupts the cohesion of wet sand that, otherwise, results inthe problem discussed above in context of FIG. 1.

According to one embodiment, a proppant container is constructed andarranged for use in transporting sand and dispensing sand. The proppantcontainer may be improved by the addition of a vibrator assemblyadapting the container for dispensation of wet sand.

In one aspect, the proppant container may include sidewalls forming abox that descends into a hopper. The vibrator contacts the walls or thehopper to facilitate discharge of sand through a gate that governs thedischarge of sand through the hopper. In the alternative, the vibratormay be part of the box, attached to or removed from the box, mounted onthe conveyor or mounted on a separate stand between the box andconveyor. The cohesion between proppant grains may also be broken toimpart proppant flow by aeriation. The aeriation will break the cohesionwith air flow into the proppant pack directly or by causing a similarvibration previously described using a vibrator.

In one aspect, wet sand removed from the proppant container by thevibration system may feed onto a belt or drag link system. That systemmay feed the blender's sand hopper which may require a vibration systemor feed directly to blender tub. If it feeds direct to blender tub, asoftware control system tied to blender fluid parameters, such as flowrate and density, may deliver proppant direct to the blender tub basedon design requirements for proppant concentration in the frac treatment.

In one aspect, a wash system is optionally provided to spray water oranother liquid inside the proppant container to facilitate thedispensation of sand from the container. The wash system may be utilizedalone or in combination with the vibrator. The wash system sprays into acontainer inlet and washes sand towards a container outlet.

A plurality of these containers may be utilized on a rack that isequipped with a wash system arranged to facilitate dispensation of sandfrom at least one of the proppant containers. In one aspect, anautomated flow controller is constructed to obtain density and flowrateinformation, and to form a slurry within design specifications to feed ablender tub for a hydraulic fracturing operation over a period. Thistype of system has no need of a conveyor belt in transporting sand forthe containers to a blender tub.

In one aspect, the wash system may include a water source and a troughthat receives both sand and water for slurry formation. The wash systemmay also include a loop for recirculating the slurry through the trough.A level indicator in the trough permits the automated flow controller tomaintain slurry within the trough at a level within a range sensed bythe level indicator.

According to one embodiment, the automated flow controller is programmedin a loop that first determines a flowrate adjustment as needed forconformity with design specifications, then determines a densityadjustment. The automated flow controller may operate by wireless meansto communicate with a plurality of densitometers, flowmeters, and pumpson the rack.

According to one embodiment, a computer readable storage medium has datastored therein representing software executable by a computer. Thesoftware includes instructions to automate flow control during ahydraulic fracturing operation. These instructions are operable for:obtaining hydraulic fracturing job design parameters including at leastproppant slurry flowrate and proppant slurry density values; receivingsensed proppant slurry flowrate and proppant slurry density valuesduring performance of the hydraulic fracturing job; determining whetherthe sensed proppant slurry flowrate is according to design specificationand, if the sensed proppant slurry flowrate is out of specification, fordetermining a flowrate adjustment as needed to bring the flowrate withinspecification; and determining whether the sensed proppant slurrydensity is according to design specification. If the sensed proppantslurry density is out of specification, the software includesinstructions for determining a mass adjustment as needed to bring thedensity within specification. The software also permits the automatedflow controller to implement the flowrate and density adjustments byadjusting the output of various system pumps.

In one aspect, a knife edge gate may be utilized to make a ribbon ofproppant having a substantially uniform thickness as the proppant isdispensed from a surge hopper onto a conveyor belt. This uniformthickness facilitates volumetric control of the proppant by adjustingthe speed of the conveyor belt, which is useful for purposes ofascertaining proppant flow rates in context of mass flow control. Asurge hopper of this nature may have a top opening that tapersdownwardly to a discharge opening, and at least one sidewall with a sideopening therethrough. A pair of opposed vertical channels are mounted onthe hopper proximate the side opening. A plate is slidingly engagedwithin the pair of opposed channels to cover the side opening at aselected height. A clamp assembly retains the plate at a fixed positionrelative to the side opening. The clamp assembly may be used forselective adjustment of the height of the plate above a conveyor beltwhere the thickness of the ribbon of sand coincides with the height ofthe plate above the conveyor belt.

According to various embodiments, the system may utilize variousstrategies for dust mitigation when dry sand is in use. This mayinclude, for example, a mist spray system, a baghouse, a closedoperator's quarters, and an agglomerating yoke.

In one embodiment, a misting system is provided for the mitigation ofdust. The misting system contains conveyor system having an endless beltand a discharge area. A water supply feeds a spray head assembly that ismounted proximate the discharge area of the conveyor system. The watersupply system includes at least a hose or pipe connecting the watersupply to the spray head assembly and may include also a heater to warmwater in cold climates, a chemical injector for treating the water, afilter, and a pump to pressurize the water. The spray head assembly isconfigured to emit a fine mist encompassing the discharge area such thatwater droplets coalesce on dust particles emanating from the conveyorsystem at the discharge area when the conveyor system is in use todispense proppant in support of a hydraulic fracturing operation,whereby the water droplets remove dust from the air.

In various preferred aspects, the misting system may include a valve foradjusting pressure in the tubular member downstream of the pump forcontrol of flow rate through the spray head assembly. The pump may bepowered electronically, or with a power take off from the conveyorsystem. The spray head assembly may be formed using, for example, atubular body in a geometric shape commensurate with a pattern coveringthe discharge area. A plurality of spray heads mounted on the tubularbody may be arranged to emit water over the pattern. The geometricpattern may be, for example, that of a bar, an arc or a circle.

The spray heads of the misting system preferably include at least oneatomizing spray head that accepts an air supply to facilitateatomization or fogging of the water. Spray heads of this type may bepurchased on commercial order to emit water in predetermined amounts,such as from 0.03 to 0.25 gallons per minute (gpm), 0.05 to 0.5 gpm, 0.5to 1.5 gpm, 0.7 to 7 gpm, 1.3 to 13 gpm, or 10 to 30 gpm. These rangesencompass the range of what rates of water may be emitted from a singlespray head, as well as a plurality of spray heads on the spray headassembly.

According to one embodiment, a dust mitigation system used in hydraulicfracturing operations may contain a baghouse. A conveyor assembly havingan endless belt is configured to discharge proppant into a dischargearea. A cover encompasses the discharge area for containment of dustemanating from the proppant when the conveyor system is in use. Thecover isolates the discharge area as an interior space within the coverand has an opening for passage of the conveyor assembly into theinterior space. A blower is deployed on the cover to pull outside airalong a pathway through the opening, into the interior space, through afilter, and then outside of the interior space. This arrangement forms,for example, a selectively positionable baghouse that may be used at thepoint of any proppant transfer, such as the discharge of one conveyorsystem info a bin or hopper, or at any point where a first conveyorsystem transfers proppant to a second conveyor system.

In one aspect, the cover has a top, with the blower and filter residingon the top of the cover. This permits trapped proppant dust to falldownward where the dust may be recycled into the flow of proppant thatis used for fracturing the well. To facilitate cleaning of the filter,the blower may be configured for selective activation to move airbackwards on the pathway as needed for cleaning of the filter.

The cover may be made of a fabric, steel or a composite. In the case offabric, the cover and blower are supported by a frame, which may be aninternal or external frame. The fabric cover may be attached to theframe using rope that passes through eyelets on the cover and wrapsaround the frame.

The filter may be any type of filter or combination of filters, such asa size exclusion filter cyclonic filter, or a high throughput filterthat is enhanced by the use of corona charging such as is reported inU.S. Pat. No. 5,549,735 to Coppom, which is incorporated by reference tothe same extent as though fully replicated herein.

According to one embodiment, the dust mitigation system or apparatus,may include an agglomerating yoke. A yoke body has an upper inlet and alower outlet such that proppant may flow through the yoke body under theinfluence of gravity. A flow passage through the yoke body connects theupper inlet with the lower outlet. A door assembly is provided that isnormally biased into a closed position covering the lower outlet. Thedoor assembly has at least a first door and may have a plurality ofdoors operating in opposition to restrict flow of proppant from the yokebody. A pivot is provided to permit axial pivoting of the first doorbetween the closed position covering the lower outlet and an openposition that is pivoted outwardly away from the lower outlet. A firstcounterweight assembly resides on the door at a position such thatgravity acting upon a counterweight biases the door into the closedposition. The first counterweight assembly has a mechanism permittingselective movement of the counterweight to increase or decrease theamount of bias exerted by the first counterweight assembly on the firstdoor under the influence of gravitational forces. The bias exerted inthis manner is sufficient to delay the passage of proppant through theflow passage as proppant is flowing form the upper inlet towards thelower outlet, creating a residence time within the flow passagesufficient for the agglomeration of dust. This residence time may be,for example, suitably from 1 to 3 seconds or more.

The door assembly preferably includes a second door and a secondcounterweight assembly operating in tandem with the first door and thefirst counterweight assembly for the mitigation of dust.

In one aspect, the first counterweight assembly or assemblies mayinclude a hydraulic actuator constructed and arranged to move thecounterweight in a manner that varies the leverage exerted by gravity onthe corresponding door. This mechanism may additionally include a motivemeans, such as a hydraulic actuator or gearing system. By way ofexample, a radio-actuated electric motor may be configured to drive thehydraulic actuator or gearing system based upon control signalsoriginating from an operator's panel.

The yoke body is preferably located to receive proppant as the proppantdischarges from the discharge element of a proppant motive mechanism,such as a conveyor belt or drag link system. The upper inlet of the yokebody is then positioned to receive proppant from the discharge elementwhen the proppant motive mechanism is moving proppant. The yoke body isalso positioned to discharge into a bin, another hopper, or the inlet ofa second conveyor located beneath the lower outlet of the yoke body.

Preferred but optional embodiments include protection from overfill ofthe yoke body. Where the yoke body is set up to discharge into a seconddevice, such as a bin or hopper, it is preferred that the upper inlet ofthe yok body is smaller than the inlet into which the yoke body isdischarging. In this manner, spillage from the yoke body overflows intothe second structure. Spillage of this nature indicates a need to adjustthe counterweight assemblies to exert less force on the doors upon whichthe counterweight assemblies reside.

In preferred embodiments, the yoke body tapers downwardly from the upperinlet to the lower outlet, and the flow passage of the hoke body may beprovided with baffles, plates, or rods to retard the flow pf proppantthrough the flow passage. The dust mitigation apparatus may be used incombination with other dust mitigate devices, such as the baghouse orthe mist spray system described above.

Another such improvement is an isolated control room that provides asafe environment protecting equipment operators from excessive dustexposure. Any roadable piece of surface equipment for use in a hydraulicfracturing operation may be provided with a control cabin that ismounted on the surface equipment. The control cabin may include acovering, such as a fabric, steel or composite material, that definesand isolates an interior space. A door, such as a flap in the cover or aframe with a hinge mounted door, electively isolates the interior spaceand may be selectively opened to provide egress to and from the interiorspace. An operator's control panel resides in the interior space and isconstructed and arranged to permit an operator to control one or moreaspects of a hydraulic fracturing operation. A blower may be provided,for example, to push air into the covering to provide a positivepressure environment therein relative to ambient pressure outside thecovering when the door is isolating the interior space. A filteroperates in conjunction with the blower for removal of dust from thethat is air pushed by the blower.

In one aspect, the blower may form part of a heating or cooling system,such that the air pushed by the blower travels across a heat exchangerfor heating or cooling system. The surface equipment may be, forexample, a conventional blending unit, a conveyor sled assembly, apumping unit, or a frac van that is improved by retrofitting to install,the isolated control room described above.

It will be appreciated that any of the foregoing instrumentalities maybe utilized to provide their respective purposes of fracking a well withwet sand, flow control, or dust mitigation when performing a hydraulicfracturing operation to stimulate a well. These instrumentalities may beused alone or in combination.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a midsection view of proppant container of the prior art,showing a problem that arises with the use of wet sand;

FIG. 2 shows a proppant container that has been fitted with a vibratorenabling the use of wet sand;

FIG. 3 provides additional detail regarding the proppant container withthe vibrator;

FIG. 4 shows a wet sand feeder system that is equipped to utilize aplurality of containers that are filled with wet sand and has a liquidwash system for enhanced flow control of sand going into a blender tubthat is used in a hydraulic fracturing operation;

FIG. 5 is a diagram of computer logic for flow control of the systemshown in FIG. 4;

FIG. 6 shows an alternative sand distribution system that utilizes adrag link in place of a conveyor belt;

FIG. 7 shows a sand distribution system that is equipped with a vibratormounted upon a stand that supports one or more proppant container;

FIG. 8 shows a conveyor sled assembly that is used as a sanddistribution system that is provided with a plurality of vibratorassemblies that facilitate distribution of wet sand onto a T-belt;

FIG. 9 shows an elevator or metering conveyor according to oneembodiment for use in moving wet proppant;

FIG. 10 shows the metering conveyor in a roadable state;

FIG. 11 is a diagram of programmable logic that may be used by a flowcontroller to drive various components of sand moving equipment insynchrony according to rate and density setpoints for a hydraulicfracturing job;

FIG. 12 shows a proppant container with a hopper that is fitted withumbrella valves to facilitate discharge of wet sand;

FIG. 13 shows an umbrella valve.

FIG. 14 shows a surge hopper configured with a knife-edge gate used toproduce a ribbon of sand having a substantially uniform thickness on aconveyor belt;

FIG. 15 shows the rear of the surge hopper equipped with a heightadjustment mechanism;

FIG. 16 shows a discharge chute including a mist sprayer assembly fordust mitigation when transferring proppant into the surge hopper;

FIG. 17 shows a water processing system for the mist sprayer assembly;

FIG. 18 shows a bag house covering the surge hopper for purposes of dustmitigation;

FIG. 19 shows the surge hopper supporting an interior frame for supportof the baghouse;

FIG. 20 shows an agglomerating yoke that compacts sand or other proppantexiting a discharge chute for purposes of dust mitigation;

FIG. 21 is a midsectional view of the agglomerating yoke;

FIG. 22 is a top plan view of the agglomerating yoke;

FIG. 23 illustrates a hydraulically actuated counterweight arm thatforms part of the agglomerating yoke;

FIG. 24 illustrates the components of a servo package that controlsoperation of the hydraulically actuated counterweight arm;

FIG. 25 shows an isolated control room positioned on a conveyor sled toprotect an operator thereof from exposure to silica dust;

FIG. 26 provides additional detail with respect to the isolated controlroom;

FIG. 27 shows an alternative drag link mechanism having an upwardlyrising section;

FIG. 28 shows an alternative sand distribution system in which a sandmotive mechanism is supported by elastomeric links that function asdampers;

FIG. 29 shows an alternative knife edge gate assembly mounted on aconveyor sled to produce a ribbon of sand having a substantially uniformthickness on a conveyor belt;

FIG. 30 shows a layout of frac equipment with use of containerized drysand according to one embodiment; and

FIG. 31 shows a layout of frac equipment with use of containerized wetsand according to one embodiment.

DETAILED DESCRIPTION

There will now be shown and described, by way of non-limiting examples,various instrumentalities for overcoming the problems discussed above.

Wet Sand Dispensing Equipment.

The ability to dispense wet sand has advantages in cost reduction, asdiscussed above, as well as dust mitigation. However, the surfaceequipment presently in use for dispensing sand during a hydraulicfracturing operation is incapable of dispensing wet sand. Theinstrumentalities disclosed below advance the art by permitting the useof wet and/or unprocessed sand while providing also for dust mitigationsufficient to meet newly emerging regulatory requirements.

Vibratory Action

FIG. 2 shows a proppant container 200 that has been equipped tofacilitate the use of wet proppant during a hydraulic fracturingoperation. The container 200 has an interior 201 that is defined by anopposed system of four vertical rectilinear sidewalls, such as sidewall202, and a hopper 204 leading to a sand outlet at discharge gate 206.The sidewalls 202 are supported by a frame that includes a plurality ofupright members 208, 210, horizontal members 212, 214 and internalcrease members 216. Corners of the frame may be provided with intermodalconnectors 218. A top hatch assembly 220 forms an inlet that is used tofill the interior 201 of container 200 with proppant, such as sand orceramic proppants. The gate 206 is optionally a ladder gate, a clamshellgate, or an iris gate that may be mechanically opened and closed for theselective discharge of proppant.

A lower frame assembly 222 circumscribes the hopper 204. The walls ofthe hopper 204 reside at an angle “A” that facilitates the discharge ofdry proppant. The angle A preferably rises by at least 35° relative tohorizontal. Forklift tubes 224, 226 are made to receive the tongs of aforklift for moving the container 200. The forklift tubes 224, 226 arewelded to horizontal support members 214. Risers 228, 230 connect theforklift tubes 224, 226 to an upper horizontal frame member 232 that iswelded to the hopper 204.

A vibrator 234 driven by electric motor 236 provides sufficientvibration to cause wet sand within container 208 to discharge throughgate 206. The vibrator 234 applies the vibratory force to the hopper204, which facilitates the discharge of wet sand from the interior 201.The electric motor 236 imparts rotary motion to a set of eccentricweights that impart an omnidirectional vibratory force. One example ofcommercially available electronic industrial vibrators suitable for thispurpose includes the Model 4P Series of vibrators from Metalfab, Inc. ofVernon, N.J. These vibrators have a range of sizes with adjustableweights for control of the amplitude of vibration. Depending upon themodel selected and the weight adjustment settings, these vibrators maydeliver from 300 to 15,000 pounds of vibratory force with 1800vibrations per minute. The frequency of vibration may be controlled as afunction of rotational velocity of the motor of the vibrator 234. In onesuch example, there is a Model 4P-1.4K™ that weighs 63 pounds andproduces one horsepower of vibration that delivers 1400 pounds ofvibrational force and draws 3 amps at 230 volts or 1.5 amps at 460volts. Although FIG. 2 shows the vibrator 234 contacting the hopper 204,the vibrator 234 may be mounted on any part of the container 200,attached/removed from the container 200, mounted on a conveyor sled(shown below) or mounted on a separate stand between the container 200and the conveyor. The vibrator 234 is connected to a source ofelectricity from the conveyor (not shown). For the conveyor-mountedcontainers according to one embodiment, it is possible to place thevibrator 234 on footing or rails where the container resides on aconveyor sled assembly in a configuration such that the vibrator 234shakes the container that resides atop the vibrator 234. More than onevibrator 234 may be installed on a container, conveyor or separate standbetween box and conveyor.

Optionally, the proppant container 200 is fitted with a female connector238 that receives a tubular male member 240 for supply of water 242 to apipe 244. The pipe 244 delivers water to internal spray nozzles 246,248. In addition to vibration, the use of water provides a secondarymeans to move sand. For example, wet sand at 15-20% by weight of watermay flow much easier than sand at 5-7%. Adding water to increase thepercentage of water improves flow while reducing amount of vibrationthat is needed to fluidize the wet sand. The amount of water deliveredin this manner may be metered and accounted for as contributing to thedesign specifications of the final frac fluid that is pumped down a well

FIG. 3 shows the container 200 from a left front top perspective. Ascrew drive 300 is used to open and close the gate 206. Additional framemembers not shown in FIG. 2 include, for example, horizontal framemembers 302, 304, 306 and vertical member 308. As shown in FIG. 4, thetop hatch assembly 220 includes a rectangular door 310 that isconfigured to seal a corresponding rectangular opening 312. Therectangular door 310 is provided with a circular hatch 314 that is easyto open when the container 200 is being filled with sand. In alternativeembodiments, the hatch assembly 220 may cover openings that have othershapes, such as a round or square opening (not shown) where there mayoptionally also be a single hatch.

Slurry Transport System with Flow Controller

FIG. 4 shows a sand distribution assembly 400 that includes thecontainer 200 sitting atop a rack 402 together with containers 404, 406,408, 410. The containers 404-410 are identical to container 200. Therack 402 includes a top rail 412 that provides predetermined seatingpositions for each of the containers 200, 404-410. The rack 402 alsoincludes a ground-contacting rail 414 and support legs 416, 418, 420,all of which are mirrored on the remote side of the rack (not shown).

A trough 422 is positioned to receive sand that is discharged from therespective containers 200, 404-410. The sand is optionally washed into atrough 422 from the containers 200, 404-410 by spray nozzles 424, 426,428, 430, 432 which may be allocated to their corresponding containers200, 404-410. The spray nozzles 422-432 receive water from water source434. The water is pressurized by the action of a centrifugal pump 436,which discharges into a rack-mounted spray feeder line 438, that feedsthe spray nozzles 424-432. A centrifugal pump 440 circulates a slurrymixture of sand and water through trough 422 and line 442 between troughinlet 444 and trough outlet 446. A flowmeter 448 in line 442 measuresthe rate of flow 450 to assure proper mixing of sand and water, as isconfirmed by a densitometer 452.

The system described above is capable of pumping slurried sand in a loopwith additions and subtractions from the flow. A centrifugal pump 454with a programmatically controlled rate of pumping removes slurry fromthe trough 422 for delivery to a blender tub 456. A flowmeter 458 anddensitometer 460 provide additional measurements characterizing the flowrate and sand content of the slurry exiting the centrifugal pump 454. Alevel indicator 462 provides signals indicating a level of slurry withinthe trough 422. A centrifugal pump 463 may be actuated on demand tointroduce additional water into the trough 422 from water source 434according to requirements as indicated by the level indicator 462.

A wireless programmable flow controller 464 receives signals from theflowmeters 448, 458 and the densitometers 452, 460 to assess the rateand content of flow within the trough 422 and into the blender tub 456.The flow controller 464 actuates the centrifugal pump 436 to washadditional sand into the trough 422 whenever slurry density needs toincrease and to compensate for sand being discharged from the trough 422through the centrifugal pump 454. The flow controller 464 actuates thecentrifugal pump 463 to introduce additional water into the trough 422whenever slurry density needs to increase and to compensate for waterdischarge from the trough 422 through the centrifugal pump 454. Thelevel indicator 462 provides a signal indicating the level of slurrywithin trough 422.

The measurement from densitometer 460 provides a density reading thatgoverns operation of centrifugal pump 466 to control a rate of mixingbetween slurry from the trough 422 and a source of frac fluidconstituents 468 as specified according to design for a particularhydraulic fracturing operation. A flowmeter 470 confirms the output ofcentrifugal pump 466 while densitometer 472 measures the density of thefrac fluid 468. The blender tub 456 is a standard blender in use forhydraulic fracturing operations and discharges a blended frac fluidmixture through line 474 for use in hydraulic fracturing operations asare known to the art. Flowmeter 476 and densitometer 478 confirm theeffluent flowrate and density of the mixture exiting blender tub 456through line 474. It will be appreciated that the frac fluidconstituents 468 may be water, in which case the supply may be fromwater source 434.

A centrifugal pump 480 may be controlled to pump a volume that mayincrease or decrease over time according to requirements for aparticular hydraulic fracturing job. The volumetric pumping rates ofpumps 454, 466 may, accordingly, be driven in synchrony with thevolumetric pumping rate of pump 480 so that the volume of proppant orproppant slurry in the blender tub 456 is sufficient to meet jobrequirements. The centrifugal pumps 436, 440, 454, 462, 466, 480 are notlimited to any particular type of pump or volumetric throughput.Centrifugal pumps are suitable for this application and, for example,may be selected to accommodate an expected flowrate of approximately 5to 20 barrels per minute. Positive displacement pumps are alternativelysuitable for flowrates on the lower end of this range. The densitometers452, 460, 472, 478 are suitably low-pressure radioactive densitometers.The flowmeters 448, 458, 470, 476 are suitably turbine flowmeters. Theflow controller 464 may communicate wirelessly with centrifugal pumps436, 440, 454, 462, 466, 480 to provide instructions governing rate ofoperation. The flowmeters 448, 458, 470, 476 may wirelessly communicatewith flow controller 464 to provide flow measurements. The densitometers452, 460, 472, 478 may wirelessly communicate with flow controller 464to provide density measurements.

It will be appreciated that the proppant distribution assembly 400 maybe divided into separable components. The centrifugal pumps 454, 466,may be located on the rack 402 or on a separate blending unit (indicatedgenerally by numeral 482), as may the blender tub 456. The flowmeters448, 458, 470 and the densitometers 452, 460, 472 may also be locatedeither on the rack 402 or the separate blending unit 482. Thecentrifugal pump 480, flowmeter 476 and densitometer 478 are downstreamof the blender tub 456 and may be located on the separate blending unit482 or in components downstream from the blending unit 482.

Flow Control Logic.

In use during a hydraulic fracturing operation, the programmable flowcontroller 464 includes an internal processor and memory (not shown)that operates using program logic 500 according to the softwareflowchart of FIG. 5. The purpose of programmatic logic 500 is to obtaindensity and flowrate information from flowmeter 476 and densitometer478, i.e., effluent flowrate and effluent density, and to maintain thiswithin design specifications for a particular hydraulic fracturingoperation over a period of time. The flow controller 464 has a memoryand processor programmed with this logic as software that may beprovided on a computer readable medium or form, such as a hard disk,CD-ROM, DVD, or thumb drive. The flow controller 464 utilizes this logicto assure that a ready stream of wet sand or fluidized sand slurry cantravel down a sand delivery system (see FIGS. 4 and 6) system and bemetered directly into the blender tub with sufficient accuracy to meetthe job design parameters and relative changes to those job parametersbased on well conditions.

The hydraulic fracturing operation is designed by means known to the artfor utilizing such data as water flowrates, fluid compositions andproppant flowrates. The programmable flow controller 464 obtains 502this data, for example, as operator input or a downloaded data file. Thedesign may be performed, for example, by using commercially availablesoftware packages, such as Elfin Tgr™ by Rockfield of Houston, Tex., orFracPro™ by Carbo Ceramic, also of Houston, Tex. As the hydraulicfracturing job is underway, the programmable flow controller 464receives 504 sensed measurements of effluent flowrate and density fromflowmeter 458 and densitometer 460. The logic 500 consults thepredetermined design criteria for the hydraulic fracturing operation andqueries 506 whether the effluent flow rate sensed by flowmeter 458 isexceeding the output of blender tub 456 as sensed by flowmeter 476. Ifso, then the programmable flow controller 464 acts to prevent 508 theresulting blender tub overflow condition, preferably by signaling anincrease in the pumping rate of pump 454. The program next queries 510whether the effluent flowrate sensed by flowmeter 458 is according todesign specifications. If the flowrate is out of spec, the programmableflow controller 464 adjusts the flowrate 512 by controlling the speed ofcentrifugal pump 454. The program 500 then consults the predetermineddesign criteria for the hydraulic fracturing operation and queries 514whether the effluent density is according to design specifications. Ifthe density is out of spec, the flow controller 464 adjusts the density516 by controlling the speed of one or more of centrifugal pumps 436,462. Generally speaking, the output of centrifugal pump 436 is increasedto correspondingly increase slurry density in trough 422 by washing sandfrom containers 200, 404, 406, 408, 410. The output of centrifugal pump463 is increased to add water from water source 434, thereby decreasingdensity. This is not necessarily an operation where either pump 436 orpump 463 is activated in isolation, for example, since it may be thecase that both volume and density need to increase. The process thenrepeats itself by receiving 504 new sensed effluent flowrate and densitymeasurements. These measurements may be averaged over time to preventadjustments that are too rapid for practical effects to occur.

One way of determining the flowrate adjustment in step 512 is tocalculate a value according to Equation (1):ΔQ=Q _(D) −Q _(T)  (1)

where ΔQ is the flowrate adjustment needed to achieve designspecifications, Q_(D) is the flowrate according to designspecifications, and Q_(T) is the volume exiting the blender tub 456.

Density may be adjusted in step 516 according to Equations (2) and (3):M _(A) =Q _(E)(ρ_(D)−ρ_(E))+ρ_(D) ΔQ  (2)

where M_(A) is the additional mass per unit time that is required toachieve density ρ_(D) according to design specification when adjustingflowrate ΔQ, Q_(E) is the effluent flowrate exiting trough 422, andρ_(E) is the density of effluent from trough 422.

The value M_(A) may be achieved according to Equation (3):M _(A) =M _(S) +M _(W)  (3)

where M_(S)s is the mass flowrate of water from water source 434, andM_(W) is the mass flowrate of slurry emanating from washing thecontainers 200, 404-410. M_(W) is determined by use of an empiricalcorrelation that determines the amount of sand and water that exits thecontainers 200, 404-410 based upon an input of wash water. This is aniterative solution for convergence on M_(A) that begins with a guess,such as the input of wash water M_(W) equals the volume of waterrequired to fill trough 422 to a level determined by level indicator462.

The programmable flow controller 464 then implements 518 these flowrateand density adjustments by adjusting the speed of centrifugal pumps 436,462, and 454.

Drag Link System with Rate-Controlled Delivery

FIG. 6 shows an alternative wet sand supply system 600. A plurality ofcontainers 200, as described above, sit upon rails 602, 604. A drag linkdevice 605 includes a pair of chains 606, 608 constructed to carry aplurality of cross-bars or links 610, 612 in moving sand that isdischarged from the containers 200 through trough 614 towards a surgehopper 616 that feeds a blender tub 618. As shown in FIG. 6, the draglink device 605 runs horizontally.

The surge hopper 616 and the blender tub 618 may exist at differentelevations such that the sand from the surge hopper 616 needs to ascendfor delivery into the blender tub 618. In this type of system, in orderto avoid providing the drag link device 605 with a latter segment (notshown) proximate the blender tub 618 that rises upwardly, it is possibleto provide a separate elevator or metering conveyor assembly 622 toimpart the elevation increase between the surge hopper 616 and theblender tub 618. The blender tub 618 mixes wet sand from the trough 614with frac fluid constituents 620 from line 624 and discharges themixture through line 626 for use in hydraulic fracturing operations.

It will be appreciated that the sand supply system 600 may be providedwith densitometers, pumps, and flow meters (not shown) at appropriatecontrol points to provide for automated flow control in support of ahydraulic fracturing operation generally as described in context of FIG.4. However, in system 600 it is not necessary to carry the sand in aslurry. The sand may contain a lower water content such that the sand orproppant does not necessarily behave as a vibration-induced semiliquid.The sand may also be processed sand or dry sand with minimal use ofwater.

The drag link device 605 is equipped with a belt motive mechanism 628,such as an electrical motor or hydraulic system configured to advancethe proppant-laden fluids by movement of the crossbar links 610, 612. Alevel indicator 630 may assess the level of proppant in the surge hopper616, and this level may be calibrated to represent a volume of proppantwithin the surge hopper 616. A wireless flow controller 632 receivessignals from the level indicator 630 and adjusts the speed of the beltmotive mechanism 628 to maintain the level of proppant in the surgehopper 616 within an established range of values acting as a buffer formeeting proppant rate delivery requirements for a hydraulic fracturingoperation. The rate requirements may be established as operatorsetpoints that reflect rate requirements as determined by hydraulicfracture modeling as is known in the art, as described above. Thus, thewireless flow controller 632 utilizes the operator's setpoint or anotherrate requirement to assure that the drag link device 605 and themetering conveyor assembly 622 are driven in synchrony to meet currentproppant rate delivery requirements for the conduct of a hydraulicfracturing operation that is in-progress. The control of synchrony inthis regard is not necessarily perfect at all times, so the surge hopper616 acts as a buffer for overages and underages when the drag linkmechanism 605 and the metering conveyor 622 are transiently out of sync.Thus, the internal volume of the surge hopper 616 may vary by design asis needed to satisfy volumetric buffering requirements for the expectedoverages and underages.

Various sensor signals facilitate the programmed synchronicity functionof the wireless flow controller 622 according to one embodiment. Adensitometer 634 obtains density readings from the proppant materialwithin the surge hopper 616. A motive mechanism 636, such as an electricor hydraulic motor, turns a belt of the metering conveyor assembly 622at a speed determined by the wireless flow controller 632. The meteringconveyor assembly 622 is equipped with a load sensor 638 that providessignals indicating the weight of the proppant on the conveyor. Thesesignals may emanate, for example, from load scales on the motivemechanism 636 that sense the weight of the metering conveyor assembly622 or from a servo-driven torque gauge as described in United StatesPatent Publication 2012 0285751 to Turner or U.S. Pat. No. 9,018,544 toTurner, each of which are hereby incorporated by reference to the sameextent as though fully replicated herein. Load scales for these beltsare alternatively known as conveyor scales or belt scales and may bepurchased on commercial order for this use, providing accuracy in the±2% range. The high level of accuracy and dynamic responsiveness ofthese systems are well-suited for this use because they enhance theability of the system to maintain operator setpoints. In someembodiments, the belt motive mechanism 628 and the motive mechanism 636may be mounted in the surge hopper 616. The belt motive mechanism 628and the motive mechanism may be driven in synchrony to match operatorsetpoints for proppant demand according to design needs for a particularhydraulic fracturing job. Thus, electronic system controls, such as thewireless flow controller 632, may adjust the delivery of proppantaccording to a dynamic or changing schedule of proppant demand that anoperator may input, for example, at the blender tub 618. The operatormay also be provided with override buttons to accelerate or delay thedelivery of proppant to the surge hopper 616 there appears to be agrowing problem with proppant rate overages or underages as may bevisually assessed by an operator visually ascertaining the level ofproppant in the surge hopper 616 if the system is allowing the problemto grow in an unresolved manner.

A centrifugal pump 640 discharges the proppant/frac fluid constituentmixture from within the blender tub 618 for downstream use in hydraulicfracturing operations. A flow meter 642 measures the flowrate ofmaterial from the centrifugal pump 640 and provides signalsrepresentative of the flow rate in line 626. A densitometer 644 measuresthe density of the proppant/frac fluid constituent mixture in line 626provides signals representative of the density. The wireless flowcontroller 632 adjusts the speed of the centrifugal pump 640 to meetflow rate requirements as determined by the flowmeter 642 according tooperator setpoints that may be established by design modeling of aparticular hydraulic fracturing operation. Similarly, line 624 containsa centrifugal pump 646 under control of the wireless flow controller 632for discharge of frac fluid constituents 620 into the blender tub 618. Aflow meter 648 and densitometer 650 provide representative signals ofthe flow rate and density of the frac fluid constituents 620 in line 624over time. A check valve 652 prevents backflow from occurring from theblender tub 618 into the frac fluid constituents 620. It will beappreciated that the components fully within box 656 may reside on ablender unit, while the other components of FIG. 6 may reside on aseparate conveyor sled.

There is a mass or volumetric balance in the blender tub 618 such thatthe total amount of material discharged through line 626 should reflecta net of balance the incoming materials: (1) from the frac fluidconstituents 620, and (2) the discharge from the metering conveyorassembly 622 into the blender tub 618. Thus, the wireless flowcontroller 632 is programmed to operate the motive mechanism 636 at aspeed such that the discharge from metering conveyor assembly 622 issufficient make up for the discharge of proppant through line 626. Forstandardization, a dry weight or volume of proppant may be used to drivethis synchronicity. The wireless flow controller 632 may then cause themotive mechanism 628 to deliver proppant to the surge hopper 616 involumetric synchronicity with the discharge from the metering conveyorassembly 622 into the blender tub 618. A level indicator 654 mayoverride this synchronicity to accelerate or slow the discharge ofmaterials into the blender tub 618 if the level of materials in theblender tub 618 rise or fall outside of a predetermined operationalrange.

Using signals from the load indicator 636 and the rotational velocity ofthe metering conveyor assembly 622, it is possible to calculate the rateof ‘dry’ proppant being delivered by the discharge of metering conveyorassembly 622 into the blender tub 618. For example, even where theproppant is wet sand, the dry weight of proppant may be calculated usingEquation (4):Q _(s) =V _(ws) Xρ _(s) /t,  (4)

This assumes that any water in the wet proppant is entrained in theporosity of the proppant such that the presence of water does not alterthe bulk volume of wet proppant as compared to dry proppant, where Q_(s)is the approximate delivery rate for dry weight of proppant as weightper unit of time, V_(ws) is the volume of wet proppant discharging intothe blender tub 618 from the metering conveyor assembly 622, ρ_(s) isthe bulk density of the proppant when dry, and t is elapsed timerequired to the volumetric measurement V_(ws). It is also possible tocalculate the rate of water delivered to the blender tub 618 from themetering conveyor assembly 622 using Equation (5)Qw=Qtot−Qs,  (5)where Q_(w) is the rate of water being delivered by the meteringconveyor assembly 622 expressed as weight per unit of time, and Q_(tot)is the total rate of sand and water being delivered by the meteringconveyor assembly 622 expressed as weight per unit of time. Q_(tot) maybe assessed by use of an empirically derived relationship thatcalculates Q_(tot) as a function of the level of proppant in the surgehopper as determined by the level indicator 630, and the rotationalvelocity of the metering conveyor assembly 622. Alternatively, Q_(tot)may be calculated as a function of conveyor rotational velocity andsignals the load indicator 636 such that a percentage of the total loadis deposited each time a volume that is defined by adjacent crossbars(e.g., crossbars 610, 612) are positionally deployed for discharge intothe blender tub 618. It will be appreciated that weights may beconverted to volumes when dividing by density, and that the wirelessflow controller 632 may utilize calculations such as these whenadjusting the flow of proppant to meet operator-established setpointsfor flow rates and density of the blended frac fluid.

As shown in FIG. 6, the drag link device 605 is in coaxial alignmentwith the metering conveyor assembly 622, as determined by a common axisof elongation. In another embodiment (not shown), the elongate axis ofthe metering conveyor assembly 622 may be normal to the elongate axis ofthe drag link device 605. In other embodiments (not shown), the draglink device 605 may be replaced, for example, by the sand distributionassembly 400 shown in FIG. 4, the container support system 700 describedbelow in FIG. 7, the conveyor sled assembly 800 as described in FIG. 8,or another proppant delivery system such as that described in copendingapplication Ser. No. 15/264,352 filed Sep. 16, 2016 which isincorporated by reference to the same extent as though fully replicatedherein. Generally speaking, these proppant delivery systems areconstructed and arranged to move sand or other proppants from containerswhere the proppant resides towards a location for discharge from theproppant delivery system.

FIG. 27 shows an alternative drag link system 2700. Like numbering ofidentical parts is retained with respect to the wet sand supply system600 shown in FIG. 6. The drag link system 2700 differs from the wet sandsupply system 600 in that the drag ling system 2700 lacks the surgehopper 616 and the metering conveyor 622 as are shown in FIG. 6.Moreover, a drag link device 2702 of FIG. 27 is modified with respect tothe drag, link device 605 of FIG. 6. Designed primarily for thedistribution of dry sand in support of a hydraulic fracturing operation,the drag link system 2702 has a horizontal component 2704 and a risingcomponent 2706. The rising component 2706 rises upwardly from the levelof horizontal component 2704 to a level that is suitable for dischargeinto the blender tub 618.

Vibratory Sleds

FIG. 7 shows a container support sled 700 that has two main components,namely, a container support-stand 702 and a sand motive mechanism 704.The container support-stand 702 is isolated from the sand motivemechanism 704 so as not to cause excessive vibration therein. Thecontainer support-stand 702 includes rails 706, 708 with intermodalpins, such as pins 710, 712, 714, defining container loading areas. Legs716, 718, 720 contact the ground and may be provided with screw-mountedleveling plates (not shown) where each leg meets uneven ground. Whilebeing designed for use of vibrations to assist wet sand dispensation,the container support system 700 may also be used to dispense dry sand.

The sand motive mechanism 704 is separately supported by legs 722, 724,and may be for example a conveyor belt or drag link system as describedabove. One or more vibrators 726, as described above, may be mounted onthe rails 706, 708. The vibrator 726 is provided to facilitate thedischarge of wet sand from containers mounted on the rails 706, 708.Thus, it is possible to utilize the container mounting stand 702 incooperation with containers 200 (see FIG. 2) that have a vibrator 234 inlike manner with container 200, or else the containers need no suchvibrator and conventional containers may be utilized. The sand motivemechanism 704 may be, for example, a conveyor belt, a trough 422 forcycling slurry as shown in FIG. 4, or a drag link device as shown inFIG. 6. Isolating the sand motive mechanism 704 from vibrationsbeneficially reduces undue mechanical wear, metal fatigue, anddisruption of electrical components in the sand motive mechanism 704.

FIG. 28 shows support sled 2800 as an alternative embodiment to supportsled 700 of FIG. 7. Like numbering of identical parts is retained inFIG. 28 with respect to FIG. 7. A sand motive mechanism 2802 differsfrom the sand motive mechanism 704 in that there are no legs 722, 724(see FIG. 7) supporting the sand motive mechanism 2802. The sand motivemechanism 2802 is, instead, attached to the container support stand 702by a plurality of elastomeric links 2804, 2806, 2808, 2810, 2812, 2914.The elastomeric links 2804-2814 deflect downwardly 2816 upon loading ofthe sand motive mechanism 2802 in the manner of a spring, while alsoserving as dampers that mitigate the passing of vibrations emanatingfrom the vibrator 726 onto the sand motive mechanism 2802. Theelastomeric links 2804-2814 may in some embodiments be replaced bysprings, or there may be a combination of elastomeric links and springsin place of the elastomeric links 2804-2814. It will be appreciated thatthe vibrator 726 vibrates the container support stand 702, as well asany containers resting on the container support stand. 702, but that theelastomeric links 2804-2814 protect the sand motive mechanism from thefull intensity of these vibrations.

In yet another alternative embodiment, the sand motive mechanism isrigidly affixed to the stand 702 such that vibrations readily transferfrom the vibrator 726 to the sand motive mechanism 704. This may beaccomplished, for example, by replacing the elastomeric links 2804-2814with steel connectors.

FIG. 8 shows a conveyor sled assembly 800 including two proppantcontainers 802, 804 mounted for discharge in parallel onto a conveyorsled 806. Wall 808 of container 802 is removed from container 804 forpurposes of illustration. Hopper extensions 810, 812 respectivelydischarge into a flow diverter 814 that has nipples 816, 818 dischargingsand onto a T-belt 820, which is a parallel conveyor belt system. Lengthadjustable legs 822, 824, 826 support the conveyor sled 806. Thecontainers 802, 804 reside upon vibrator assemblies 828, 830, 832 which,in turn, are supported by beam 834. The legs 822, 824, 826 support beam834 and leg 824 also provides direct support for the T-belt 820. TheT-belt 820 operates as described in United States Patent Publication2018/0065814 to Eiden et al, which is incorporated by reference to thesame extent as though fully replicated herein. The conveyor sledassembly 800 as presently shown in FIG. 8 is, however, modified forimprovement with respect to what is shown in Eiden et al. by theaddition of vibrator assemblies 828, 830, 832 mounted on the conveyorsled assembly 800 beneath the containers 802, 804. Electronics (notshown) controlling the T-belt 820 are suitably ruggedized to withstandvibrations emanating from the vibrator assemblies 828, 830, 832. Asdescribed above, the vibrator assemblies have a system of eccentricweights to control the amplitude of vibrations, and they may be drivenat different speeds to control the frequency of vibration. It will beappreciated that the vibrator assembly 830 is a single vibrator thatcontacts a plurality of containers 802, 804, whereas the vibratorassemblies 828, 830 each contact a single container 802.

Metering Conveyor

FIG. 9 provides additional detail with respect to the metering conveyor622 (see also FIG. 6) according to one embodiment. As shown in FIG. 9,the conveyor 622 is a standalone conveyor that includes an endless belt900 which is driven at controlled speeds by an electric motor 902functioning as the motive mechanism 636 discussed above. The meteringconveyor 622 is mounted on an elongate frame 904 extending upwardly froma support nose 906 (proximate the surge hopper 616) to a discharge chute908. The support nose 906 passes through openings 910, 912 in the surgehopper 616 to position the endless belt 900 in area 914 beneath adownwardly tapering hopper component 916 that receives proppant fromproppant discharge mechanism 918 for transfer onto belt 900 in area 914.The proppant discharge mechanism 918 may be for example the sanddistribution assembly 400 shown in FIG. 4, the drag link device 605 asdescribed in FIG. 6, the container support system 700 as described inFIG. 7, the conveyor sled assembly 800 as described in FIG. 8, oranother proppant delivery mechanism.

As shown in FIG. 9, the conveyor assembly 622 has an elongate axisrunning from the support nose 906 to the discharge chute 908, and thiselongate axis is perpendicular to the elongate axis (not shown) of theproppant discharge mechanism 918. The respective axes may also be inparallel. The conveying mechanism shown in FIG. 9 preferably meters theflow of the wet or fluidized sand within 1-5% accuracy using belt scalesbelow the surge hopper 616 as to provide a consistent flow of product tothe blending unit on the basis of averaging the weight in motion overtime. The speed of the belt 900 may be governed by output from the massflow controllers 464, 632, as described above, to adjust the speed ofthe belt adjustments. The flow controllers 464, 632 may also adjust therate of discharge from the discharge mechanism 918 as needed to meet jobrequirements at a blending unit (not shown). An optional sand shaker orbuzz screen 919 may be provided to assure that the proppant does nothave rocks, bolts, roots, or other large foreign items that might ruindownstream blending boost pumps or pumping equipment. The ability of themetering conveyor to weigh the load of proppant facilitates downstreammixing of frac fluids to meet design parameters for a hydraulicfracturing operation.

The elongate frame 904 includes a fifth wheel connector 920, and iscarried upon axle assembly 922, which is shown in FIGS. 9 and 10. Theelongate frame 904 and axle assembly 922 are coupled to one anotherthrough pivots 924, 926, connecting a rigid pole 928 between theelongate frame 904 and axle 922, together tubular member with pivots928, 930 containing an extensible hydraulic cylinder 932 in atelescoping pole 933 between the elongate frame 904 and the axleassembly 922. The rigid pole 928 and hydraulic cylinder may be providedin tandem (in parallel pairs) to enhance lateral stability across theframe 904. Extension/retraction 934 of the extensible hydraulic cylinder934 causes the discharge chute 908 to pivot about the support nose 906,generally along arc 936. Locating the axle in a position that residesfurther towards the discharge chute 908 than is the center of gravity938 for the elongate frame 904. This location assures that the dischargechute 908 will pivot up and down along arc 936. This pivoting raises andlowers the position of discharge chute 908 to a height that is suitablefor discharging proppant into a blender tub, such as the blender tub 618shown in FIG. 6.

FIG. 10 shows the metering conveyor 622 in a horizontal configurationpresenting a roadable state and is connected to truck 1000 for roadtransport. In the roadable state as depicted, the surge hopper 616 isrelocated to a mounting position 1002 above the axle 622. The mountingstructure may be, for example, an intermodal pin and receiver structureor bolts (not shown) that retain the surge hopper 616 in position 1002.

Control Logic

Generally speaking, the metering conveyor 622 is provided withelectronic controls that take operator inputs and set points from theblender and make the adjustments to belt speed in order to meet thesesetpoints. The metering conveyor 622 is, accordingly, able tocommunicate with the system elements described in FIGS. 4,6,7,8 tocontrol the speeds of discharge of the sand into the surge hopper 616.FIG. 11 shows program logic 1100 that may be utilized in the memory andprocessor of the wireless flow controller 632 according to oneembodiment for maintaining proppant rate synchrony as discussed abovewhile also maintaining quality of blended frac fluid exiting the blendertub 618. Before the hydraulic fracturing job can begin, it is desirableto establish 1102 setpoints for the job. The setpoints include data thatis normally provided in the performance of a hydraulic fracturingoperation, such as pumping pressures, flow rates of the frac fluid,constituents of the frac fluid, and limits for a particular stage ofpumping. Thus, for example in a slick water frac operation, thesetpoints may include the rate of proppant being pumped, pressuredownstream of the pumping unit, and frac fluid density, as well as anyother data that is used in performing a hydraulic fracturing operation.These setpoints may be determined by the use of modeling as describedabove.

The program operates upon sensors mounted on the surge hopper 616 asdescribed above to determine 1104 whether the level of material in thesurge hopper 616 is within an established range of values. As explainedabove, this range of values may vary by design, but exists within arange that is suitable for use as a buffer such that there may be atemporary imbalance of proppant rate synchrony assessed as input to anddischarge from the surge hopper 616. If the level is outside this range,the program determines 1108 whether the level is too high. If so, thenthe program causes the wireless flow controller 632 to decrease 1110 therate of proppant being delivered to the surge hopper 616. This may bedone, for example, utilizing an experiential-based empirical correlationof parameters affecting the rate of proppant delivery. If the levelwithin the surge hopper 616 is not too high 1108, then the wireless flowcontroller 632 increases 1112 the rate of proppant delivery.

The program next inquires 1114 whether the proppant rate setpoint isbeing met. If not, the program inquires 1116 whether the current rate ofproppant delivery is below the setpoint. If so, the program causes thewireless flow controller 632 to increase 1118 the rate of proppant thatis being carried from the surge hopper 616 along the metering conveyor622. This increase may be provided, for example, as a rate adjustmentdetermined by use of an experiential-based correlation that relates therate of proppant being carried by the metering conveyor 622 to one ormore such parameters as power consumed by the belt motive mechanism 636,or rotational velocity or the belt motive mechanism of the belt.

The program next inquires 1120 whether the blended frac fluid exitingthe blender tub 618 meets the density setpoint. If not, then the programcauses the wireless flow controller 632 to adjust 1122 the density ofthe blended frac fluid within the blender tub 618 to meet the setpoint.This may be done, for example, by calculations assuming the proppantdelivery rate will hold constant and then adding more or less of thefrac fluid constituents 630 as needed for the density adjustment. Withthese adjustments being made, all pumps of the system are operated at asteady state 1124 for an interval of time that is sufficient to avoidflow adjustments that are too rapid in nature, but which in the case ofa continuing lack of synchronicity also avoids overcharging the surgehopper 616 such that spillage occurs or undercharging the surge hopper616 such that an insufficient amount of proppant is being delivered tothe metering conveyor 622.

Pneumatic System

FIG. 12 shows a proppant container 1200 that is modified with respect tothe proppant container 200 of FIG. 2. In place of the vibrator assembly234 as shown in FIG. 2, the container 1200 is provided with a pneumaticsystem 1202. The pneumatic system 1202 may be purpose-built for use onnew proppant containers, or else it may be provided as a retrofitassembly used to improve existing containers. The container 1200 hasforklift tubes 1204, 1206 that are welded to cross-member 1208. Risers1212, 1214 extend upwardly from the forklift tubes 1204, 1206 to supporta rectilinear frame 1216 that contacts four walls 1218 (only one isshown in FIG. 12) of a descending pyramidal hopper 1220 that dischargesthrough opening 1222. It will be appreciated that there may be a totalof four risers such as risers 1212, 1214, and that two of them arehidden from view from the perspective of FIG. 12.

The pneumatic system 1202 includes a compressed air tank 1222 with aquick-connect air fitting 1224. The air tank 1223 discharges to apneumatic rail 1226 that supplies compressed air to disk fluidizers1228, 1230, 1232. While this embodiment presents at least one diskfluidizer on each wall, the actual number needed will be based on thetype of disk fluidizer and the energy needed to start and maintainproppant flow. The disk fluidizers 1228, 1230, 1232 pass through therespective walls 1218 to discharge air into the interior of thecontainer proximate the interior wall surfaces thereof (not shown).Suitable disk fluidizers may be purchased on commercial order, forexample, as “Disk Fluidizers” from Solimar Pneumatics of Minneapolis,Minn. These disk fluidizers are hereby defined to be in the class ofumbrella valves.

FIG. 13 shows the disk fluidizer 1228 in expanded detail. An exteriorlythreaded hollow valve body 1300 passes through wall 1218. Nut 1302secures the valve body 1300 in place. A gasket 1304 seals against theflow of air through opening 1306. The valve body 1300 permits passage ofair 1308 (from tank 1222) towards nozzle 1309, which redirects the air1308 generally parallel to wall 1218. An elastomeric cup 1310 hasgenerally a frustoconical shape that is generally concave facing thewall 1218. The elastomeric cup 1310 compressively retained on valve head1312. The elastomeric cup 1310 transiently forms a compressive sealagainst wall 1218 at periphery 1314. Upon exiting nozzle 1309, the air1308 acts upon inner surface 1316 with sufficient force to disrupt thetransient seal at periphery 1314. In the intended environment of use,this disruption causes the elastomeric cup to vibrate 1318 up and down.The vibration 1318 works together with the flow of air to dislodge wetsand form the face 1320 of wall 1218. Sand that is dislodged in thismanner is then able to discharge from the hopper 1220 (see FIG. 12).When the air 1308 is not flowing, the elastomeric cup 1310 prevents sandfrom clogging the nozzle 1304.

It will be appreciated that the aforementioned disk fluidizer systemrenders obsolete silo-based proppant drying systems as described in U.S.Pat. No. 10,017,686 to Babcock et al. which is incorporated by referenceto the same extent as though fully replicated herein. This is becausethe disk fluidizer system is not intended to render the proppant bonedry as taught by Babcock et al. Accordingly, proppant silos may befitted as described above with vibrator assembles and/or disk fluidizersfor the purpose of dispensing wet sand, as opposed to the purpose ofdrying sand or another proppant. In one example of this type ofarrangement, it is possible to have a silo acting as the proppantdischarge mechanism 918 (see FIG. 9) discharging wet sand directly intothe surge hopper 616.

Knife Edge Gate

FIG. 14 provides additional detail with respect to the surge hopper 616according to one embodiment. A hopper element 1400 has a top opening1402 for receipt of proppant therethrough. Walls 1404, 1406 tapertowards a bottom opening 1408 that discharges onto a separate conveyorbelt 900. A plate 1410 is slidably received at opposite ends in channels1412, 1414 such that sliding motion of the plate 1410 within channels1412, 1414 varies the height H of bottom edge 1416 above the belt 900.Thus, the position of bottom edge 1416 assures that a ribbon of proppant(not shown) of a predetermined uniform thickness H will exit the hopperelement 1400 atop belt 900. The plate 1410 is attached to a forwardlyextending shelf member 1418 that is provided for ease of manualadjustment, and at least partially covers an opening 1419 in wall 1406to vary the amount of this opening that is available for the flow ofproppant. A brace 1420 extends between the channels 1412, 1414, andcarries bolt 1422 which may be tightened for compression against theplate 1410 to lock the plate 1410 in a fixed position for maintenance ofthe height H. The plate 1410 in this locked position may be referred toherein as a knife edge gate. In operation, the knife edge gate producesa uniform ribbon of wet or dry sand of consistent thickness H, whichassists in metering for purposes of flow control as described above.

Use of the knife edge gate described above enables easy calculation ofvolumetric rates for purposes of flow control as described above. Thisis because the uniform has a fixed width and a uniform height, whichmeans that the volumetric flow rate is a f unction of the belt velocity,i.e.:V _(s)=HXWXV_(b) Xt  (6)where V_(s) is the bulk volume of sand, H is the ribbon height, W is theribbon width, V_(b) is the linear velocity of the belt, and t is time.

It will be appreciated that the surge hopper 616, when optionallyequipped with the vibrator 1628, may be provided as a standalone pieceof equipment that when in use does not physically contact any otherequipment as a way to protect other equipment from vibration.

FIG. 15 shows the surge hopper 616 from a rear perspective. The hopperelement 1400 is supported in position over the belt 900 by a frame 1500with ground-contacting legs 1502, 1504, 1506. A screw assembly 1508 isused to alter a distance D for selective positioning of bottom edge 1510above the belt 900. The tolerance of the resulting junction 1512 betweenthe bottom edge 1510 and the belt 900 is preferably sufficient toprevent significant leakage of proppant, such as a gap a gap that is1/32, 1/16, ⅛, or ¼ inch.

FIG. 29 shows an alternative knife edge gate assembly 2900. As shown inFIG. 29, portions of the plate 1410 and channel 1414 are removed forpurposes of illustration to reveal the opening 1419 in wall 1406residing behind the plate 1410. In this embodiment, the channels 1412,1414 are not mounted on the surge hopper 616. The channels 1412, 1414are, instead, attached to the metering conveyor 622 by the use ofL-brackets 2904, 2906 such that the plate 1410 resides in closeproximity to the wall 1406 and is able to control the ribbon of sandemanating from opening 1419.

It will be appreciated that unprocessed sand which has been freshlymined may be wet or dry, and that conventionally the sand is dry.Therefore, the improvements to sand distribution equipment alsocontemplate dust mitigation attributes as described below.

Dust Mitigation

Mist Sprayer Assembly

FIG. 16 provides additional detail with respect to the proppantdischarge mechanism 918 according to one embodiment. The proppantdischarge mechanism 918 is fed by a conveyor belt or drag link mechanismas described above, and discharges proppant 1600 into a top opening 1602of the surge hopper 616. The proppant may be wet or dry. The top opening1602 is covered with a wire mesh 1604 to remove stones and other debristhat may hinder operation of a frac pump (not shown). As shown in FIG.16, the proppant discharge mechanism 918 is improved by the addition ofa mist sprayer assembly 1606 for dust mitigation. A tubular member 1608,which may be a pipe or a hose, carries pressurized water to a tubularbody 1610 that discharges water from misting heads 1612, 1614, 1616,1618, 1620, 1622. Water exiting the misting heads 1612-1622 forms a mistzone 1624 that slightly wets the proppant 1600. The water in mist zone1624 also congeals on airborne dust particles in the mist zone 1624,with the effect of causing the dust to fall out of the air and down ontothe proppant 1600 as the proppant 1600 passes through the wire mesh1604. Thus, the mist zone 1624 preferably has an extent that willcapture airborne dust particles anywhere above the opening 1602. Thetubular member 1610 is sealed at ends 1624, 1626 to increase misting bya boost of internal pressure. The mist zone 1624 forms a barrier thatcaptures dust emissions in the atmosphere and may, for example, beemitted by misting heads having a central axis of discharge pointed in adirection ranging from 30° to 90° relative to horizontal. While anatomized mist is preferred, the misting heads 1612-1622 may be replacedwith spray heads that emit a spray of water that is not atomized.Generally speaking, the amount of water introduced to the proppant 1600through mist zone 1624 is negligible. It will be appreciated that themist sprayer assembly 1610 may be replicated on the discharge chute 908metering conveyor 622 (see FIG. 9) or anywhere that there is an exchangeor other movement of proppant exposed to air.

The misting heads 1610-1622 are optionally but preferably of the typeknown as atomizers or foggers. This type of spray head emits water inthe form of what appears to the eye as a fog and may utilize acompressed air supply 1625 to enhance the quality of the fog. Sprayheads of this type are sold commercially, for example, as the FloMax®Air Atomizing Nozzles by Spraying Systems Co. of Hamburg, Germany. Thesenozzles may be made individually to emit water at rates of from 0.03 to0.25 gallons per minute (0.11 to 0.94 liters per minute), 0.05 to 0.5gallons per minute (0.19 to 1.89 liters per minute), 0.5 to 1.5 gallonsper minute (1.89 to 5.67 liters per minute), 0.7 to 7 gallons per minute(2.6 to 26.5 liters per minute), 1.3 to 13 gallons per minute (4.9 to49.2 liters per minute), and 10 to 30 gallons per minute (38.7 to 114liters per minute). The spray head assembly preferably includes at leastone atomizing spray head and may include a combination of pneumaticallydriven foggers and misters.

Optionally, a vibrator 1628 may be attached to the surge hopper 616 toassist in shaking of the wire mesh 1604 to facilitate the flow ofproppant 1600 therethrough. As shown in FIG. 16, the surge hopper 616has a frame 1630 supporting four sidewalls 1632 that taper downwardlytowards a bottom discharge opening 1632, the sidewalls defining aninterior flow passageway from the top opening 1602 to the bottomdischarge opening 1634. The wire mesh 1604 is located at the top opening1602 and preferably has a screen size that prevents rocks and otherdebris from passing through the wire mesh 1604 if the debris has a sizethat would interfere with the operation of frac pumping units (notshown) downstream of the surge hopper 616. This is preferably a meshsize that removes debris having a diameter larger than ½ inch andpreferably the mesh size removes debris with a diameter larger than ¼inch or ⅛ inch. Generally speaking, the mesh size should remove anydebris that will interfere with intake valves of a frac pump, which isnormally in the range of debris having a minimum dimension ranging fromabout 1/16 to ½ of an inch., and preferably from ⅛ to ¼ inch. Suitablemesh sizes may be, for example, a U.S. mesh of from 2 to 14, and this ispreferably a U.S. mesh size of from 3 to 6.

While FIG. 16 shows the vibrator 1628 mounted on the frame 1630,alternative options for mounting the vibrator 1628 include a sidewalllocation 1638 and/or a wire mesh location 1640. It will be appreciatedthat, when the vibrator 1628 is mounted on the wire mesh 1604, the frame1628 and sidewalls may be isolated from vibration by the use of anoptional elastomeric damper 1636 Moreover, since the surge hopper 616 isa standalone device,

FIG. 17 shows a water processing system 1700 for the treatment of waterbefore the water enters the mist zone 1624. Water resides in a watertank 1702 and may be optionally treated by chemical injection 1704, forexample, by the addition of antifreeze or rust preventatives. The watertank 1702 is optionally heated by the provision of a heater 1706 in coldclimates where the water would otherwise freeze. A power takeoff 1708receives power from a conveyor belt 1710, which may be used todistribute or transport proppant for purposes of hydraulic fracturing asdescribed above. A pump 1712 receives power from the power takeoff 1708to pressurize water from the tank 1702. The water from pump 1712optionally passes through filter 1714 and then passes into hose 1608 fordelivery to the mist sprayer assembly 1606 (see FIG. 16). A valve 1716may be adjusted to control the pressure inside the hose 1608, and soalso the rate of water being emitted from the spray head assembly 1606.A check valve 1718 prevents backflow of water, for example, as mightotherwise be caused by an influx of air from the air supply 1625 (seeFIG. 16).

Baghouse

FIG. 18 shows a baghouse 1800 that may be used to cover the surge hopperfor dust mitigation in the event that dry proppant is in use. Thebaghouse 1800 includes a fabric enclosure or cover 1801 with rope 1802passing through eyelets 1804, 1806 and around an internal frame (notshown) of the surge hopper 616. A conveyor 1862 may be, for example, aconveyor like that shown in United State Patent Publication2018/0065814. A blower 1805 pulls air 1807 into the baghouse 1800through opening 1808. The air 1807 passes through a filter 1810 beforepassing through discharge opening 1804. The blower 1805 resides oninterior framework (not shown) over the surge hopper 616 and ispositioned such that the blower 1805 may be reversed to clean the filter1810 by dropping trapped dust into the surge hopper 616.

FIG. 19 shows the interior frame 1900 supporting the blower 1805. Theframe 1900 includes four upright posts connected by four lowerhorizontal members 1908 and four upper horizontal members 1910. Themanner of attachment using the rope 1802 and the eyelets 1804 (see FIG.18) may occur anywhere on the frame 1900.

Agglomerating Yoke

FIG. 20 shows an agglomerating yoke 2000 that may be utilized for dustmitigation. The agglomerating yoke 2000 is positioned between thedischarge chute 918 and the surge hopper 616 (see also FIG. 9). Thesurge hopper 616, for example, receives proppant 1600 as it is beingdischarged from the discharge chute 918. The mist sprayer assembly 1606creates the mist zone 1624, and dust emissions may be further mitigatedby the use of a dust shroud 2002 that envelops the region 2004 where theproppant is being discharged from the discharge chute 918. The proppant1600 passes from top 2006 and through the interior passage of adownwardly tapering yoke body 2008 to exit through proppant dischargeopening 2010. Doors 2012, 2014 are pivotally connected to the yoke body2008. Each of the doors 2012, 2014 are provided with respectivecounterweight arms 2016, 2018 such that the force of gravity exerted onthe counterweight arms 2016, 2018 acts in coordination with axial pivots2020, 2024 to exert torque 2028, 2030 biasing the doors 2012, 2014towards a normally closed position 2032 indicated by dashed lines 2032.

The purpose of the agglomerating yoke 2000 is to retain the proppant1600 within the yoke body 2008 for a time of residence while dustparticles in the proppant 1600, which would otherwise escape into theair, contact one another and particles within the proppant 1600. Thiscontact causes the dust to agglomerate so there is less dust capable ofescaping into the air at the discharge opening 2010. The doors 2012,2014 increase the agglomeration by causing the proppant 1600 to back upwithin the yoke body 2008. This increases the residence time of theproppant 1600 within the yoke body, and dust mitigation is therebyincreased because more time is allowed for the agglomeration to occur.The top 2034 of surge hopper 616 is preferably larger in all dimensionsW than is the top 2006 of the yoke body 2000. Thus, if the proppant 1600within the yoke body 2008 spills over the top 2006, the largerdimensions W cause the spillage to fall into the surge hopper 616. Itwill be appreciated that, although the embodiment of FIG. 20 has twodoors 2012, 2014, a single door may alternatively be provided.

FIG. 21 is a midsection view of the agglomerating yoke 2000 that revealsthe internal passage 2100 of the yoke body 2008. A dashed line 2102indicates a residence volume within the yoke body 2008. The line 2102varies with the volume of proppant residing in the yoke body at anygiven time and may move 2104 up or down depending upon the position ofthe doors 2012, 2014. The position of the doors 2012, 2014 variesaccording to the rate of incoming proppant and the force exerted by thecounterweight assemblies 2016, 2018. In the alternative, theagglomerating yoke 2000 may be replaced by a hopper with an internalvalve that is normally closed but is unseated by the lengthening ofsprings as the hopper fills with proppant. A system of plates or baffles2102, 2104 is optionally provides to increase residence time within theinternal passage. The residence time is suitably, for example, from 1 to3 seconds or more. An alternative yoke for use in this application isdescribed, for example, in U.S. Pat. No. 7,712,632 to Schwass, which ishereby incorporated by reference to the same extent as though fullyreplicated herein.

FIG. 22 is a top plan view of the agglomerating yoke 2000. The doors2012, 2014 are shown in a closed position under bias from thecounterweights 2016, 2018.

FIG. 23 provides additional detail about the counterweight 2016according to one embodiment. The counterweight 2016 includes an armsegment 2300 attached to a first flange 2302 that may be bolted to thedoor 2012 (see FIG. 20). The arm segment 2300 has a bend 2304. A secondflange 2306 is bolted to a portion of the arm segment 2300 remotely fromthe first flange 2302. An extensible hydraulic cylinder 2310 carries alead weight 2312 that may be shifted by extension/retraction 2314 of thehydraulic cylinder 2310 under the control of a servo package 2316.

FIG. 24 shows the elements of the servo package 2316 according to oneembodiment. The servo package 2316 is powered by battery 2400. A radioreceiver 2402 receives command signals that may emanate, for example,from a control van (not shown) on a hydraulic fracturing location. Thereceiver 2402 digitizes and passes the control signals to a processor2404 operating on program instructions from memory 2406. The processor2404 causes driver circuitry 2408 to activate a servo motor thatactuates a pump 2412. The pump 2412 draws hydraulic oil from reservoir2414 for extension of the hydraulic cylinder 2310. Reverse actuation ofthe pump 2412 by the servo motor 2410 causes the hydraulic cylinder 2310to retract. The processor and memory are able to track the degree ofextension of the hydraulic cylinder 2310, for example, using a magneticpickoff (not shown) to count the rotations of the pump 2412. Moving theweight 2312 away from the second flange 2306 (see FIG. 23) provides alever advantage that increases the torque 2028 exerted on door 2012.

Isolated Control Room

FIG. 25 shows an improved conveyor sled 2500 for the distribution ofproppant. The conveyor sled 2500 includes a frame 2502 supporting aconveyor belt 2504 that receives proppant from containers 2506, 2508,2510. The conveyor belt 2504 delivers the proppant to a rising section2512 terminating in a discharge chute 2514, which may be, for example,the discharge chute 918 shown in FIG. 9. The conveyor sled 2500resembles that shown in United States Patent Publication 2018/0065814 toEiden et al. but has been improved by the addition of an isolatedcontrol room 2516. The isolated control room 2516 is optionallyselectively detachable from the conveyor sled and may be used as anindividual unit on a standalone basis, ore the isolated control room maybe positioned on another type of frac equipment, such as a blending unitor a pumping unit (not shown). The isolated control room 2516 may alsobe used as an enhancement to frac van or in place of a frac van thatserves as a control facility governing all aspects of a hydraulicfracturing operation.

The isolated control room 2516 is a pressure-positive system thatcontains a fully functional operator's control panel and interior roomfor an operator to reside during a hydraulic fracturing operation. Asshown in FIG. 25, the isolated operator's control room is mounted on theconveyor sled 2500 but may also be suitably mounted on other equipmentknown to the art, such as a blender tub, a pumping unit or a separatetrailer. The conveyor sled 2500 is further improved by the attachment ofvibrators 2518, 2520, 2522 to the frame 2502 for use in circumstanceswhere the containers 2506-2510 contain wet sand. The vibrators are asdescribed above and shake the frame 2502 together with the containers2506-2510 sufficiently to dislodge wet sand from within the containers2506-2510.

FIG. 26 shows the isolated control room 2516 in additional detailaccording to one embodiment. The isolated control room 2506 has a top2600, a bottom 2602, and sidewalls 2604, 2606, 2608 supported by frame2610. It will, be appreciated that a fourth sidewall (not shown) ishidden in the perspective of FIG. 26. And that as shown in FIG. 26 aportion of the sidewall 2606 has been removed for purposes ofillustration to reveal the contents of an inner chamber 2612. The innerchamber 2612 contains an operator control panel 2614 with a display2616, knobs 2618, and keyboard 2620. A chair 2622 is optionallyprovided. Sidewall 2604 contains a door 2623 with a window 2624, andeach of sidewalls 2606, 2608 is provided with a portal. The variouswindows and portals provide visibility such that the operator is able toobserve the surrounding equipment in operation.

An electric blower 2628 is positioned to draw in air 2630 through filter2632, which removes dust particles from the air 2630 as the air 2630passes into the interior chamber 2612. This creates a cross-flow ofslightly overpressure air within the chamber 2612, such that filteredair 2634 exits the interior chamber 2612 through vent 2634. It will beappreciated that the blower 2628 may optionally be provided with aheating element (not shown). The filter 2632 may be replaced as thefilter 2632 becomes full of captured dust particles. The filter 2632 maybe optionally wet using a water supply to make an evaporative cooler.

FIG. 30 shows a layout 3000 of surface equipment as described above whendeployed in support of a hydraulic fracturing operation utilizing drysand according to one embodiment. Two conveyor assemblies 3002, 3002′are provided to move sand from containers 200, 200′ towards the blenderhopper 618. The conveyor assemblies 3002, 3002′ have respectivehorizontal portions where containers 200, 200′ reside. The blenderhopper resides on a blending unit 3004 that mixes the sand (or otherproppant) from the containers 200. 200′ with frac fluids from tanks3006, 3008, 3010, 3012. There may be any n umber of containers 200, 200′and any number of tanks 3006-3012. In operation, forklift operators (notshown) replace the containers 200, 200′ when empty, taking newcontainers from a container storage area 3014 as needed. Thus, therespective horizontal portions of conveyor assemblies 3002, 3002′ wherethe containers 200, 200′ reside are at a suitable height for the conductof forklift operations.

Most blender tubs like blender tub 618 rise in elevation to a heightthat is problematic for forklift operations. Thus, the respectiveconveyor assemblies 3002, 3002′ are each provided with a rising nose3016, 3016′ to lift the sand up to the blender tub 618. Mixed effluentemanating from the blending unit 3004 travels through lines 3016 to fracpumping units 3018, 3020, 3022, which pressurize the effluent forpumping through high pressure lines 3024 and into a wellhead 3026according to design parameters for a hydraulic fracturing operationintended to stimulate flow potential from a downhole formation. Forinjection wells, the stimulation may also be done to stimulate the flowpotential into an injection well. There may be any number of fracpumping units 3018-3022.

As shown in FIG. 30, the isolated control room 2516 stands alone and isnot mounted on any of the other equipment. This positioning of theisolated control room 2516, i.e., proximate the intersection of conveyorassemblies 3002, 3002′ permits one or more operators within the isolatedcontrol room to observe the proppant renewal operations as containers200, 200′ are rotated out of the container storage area 3014. Theisolated control room 2516 also resides in an area 3028 that is definedby an angle Θ extending between the elongate axes of conveyors 3002,3002′. As shown in FIG. 30, the angle Θ is a right angle, but moregenerally the angle may be suitably from 0 to 130 degrees. The angle Θmay also be an acute angle, an oblique angle, or an obtuse angle.

FIG. 31 shows a layout 3100 of surface equipment as described above whendeployed in support of a hydraulic fracturing operation utilizing wetsand according to one embodiment. In order to simplify this discussionof FIG. 31, like numbering is retained with respect to identical partsas previously described in context of FIG. 30. The layout 3100 differsfrom layout 3000 in that conveyor assemblies 3102, 3102′ are essentiallyhorizontal and do not have respective noses 3016, 3016′ rising up to theheight of the blender tub 618. Generally speaking, different types ofconveyor belts may be in use on the conveyor assemblies 3102, 3102′,such as textured or partitioned belts where the surface features of thebelt on the metering conveyor 622 is deeper than the belt of theconveyor assemblies 3102, 3102′ to prevent leakage or spillage of waterfrom the wet sand as the proppant ascents on the metering conveyor 622towards the blender tub 618.

Those of ordinary skill in the art will understand that the foregoingdiscussion teaches by way of example and not be limitation. Accordingly,what is shown and described may be subjected to insubstantial changewithout departing from the scope and spirit of invention. The inventorshereby state their intention to rely upon the Doctrine of Equivalents,if needed, in protecting their full rights in the invention.

We claim:
 1. A system for dispensing proppant, comprising: a conveyorhaving a belt that is endless and rotatable; a hopper positioned overthe belt for discharge of proppant onto the belt, the hopper having atop opening that tapers downwardly to a discharge opening located at abottom of the hopper, the hopper having at least one sidewall with aside opening therethrough, the side opening rising along the sidewall toan elevation above the discharge opening; a pair of opposed channelsmounted on the system to taper downwardly along the at least onesidewall proximate the side opening; a plate that is slidingly engagedwithin the pair of opposed channels to cover the side opening over aselected area of the side opening above the belt, the plate having astraight bottom edge; and a clamp assembly configured to hold the plateat a fixed position with regard to the side opening with the straightbottom edge of the plate being retained at a fixed height when clampedabove the belt such that when the belt is rotating and proppant isdischarging from the discharge opening and the side opening onto thebelt, the proppant forms a ribbon of uniform thickness that is useful involumetric rate calculations.
 2. The system of claim 1, wherein theopposed channels are mounted on the hopper.
 3. The system of claim 1,wherein the belt is positioned such that the belt is located beneath thedischarge opening, and the clamp assembly is holding the plate at thefixed height above the belt to dispense a ribbon of proppant having auniform thickness onto the belt.
 4. The system of claim 3, wherein theopposed vertical channels are mounted on the conveyor sled.
 5. Thesystem of claim 3, the system further comprising a screw mechanismlocated at a rear section of the hopper remote from the plate, the screwmechanism being configured for selectively adjusting a height of thehopper above the belt.
 6. The system of claim 1, further comprising anautomated flow controller utilizing program instructions for volumetricrate calculations based in part upon the thickness of the ribbon ofproppant in providing proppant according to design specifications insupport of a hydraulic fracturing operation.
 7. The system of claim 1,further comprising a scale operably configured to sense weight carriedby the belt, and an automated flow controller utilizing programinstructions for weight in motion calculations based in part upon sensemeasurements from the scale.
 8. The system of claim 7, furthercomprising a wire mesh covering the top of the hopper, the wire meshbeing sized for removal of debris from proppant.
 9. The system of claim8, including a vibrator assembly mounted to the hopper to facilitateflow of proppant through the wire mesh.
 10. A method of hydraulicfracturing to stimulate a well, comprising: delivering containers filedwith wet sand to a location where a hydraulic fracturing operation isbeing performed, and using the proppant delivery system according toclaim 1 to dispense the wet sand in support of the hydraulic fracturingoperation.
 11. A method of hydraulic fracturing to stimulate a well,comprising: delivering containers filed with wet sand to a locationwhere a hydraulic fracturing operation is being performed, and using theproppant delivery system according to claim 6 to dispense the wet sandin support of the hydraulic fracturing operation.